Assessing dual hair sampling for isotopic studies of grizzly bears.

Rationale: The stable isotope ratios of carbon (δ C values), nitrogen (δ N values) and sulfur (δ S values) in bear hair can be used to obtain information on dietary history. Sample protocols often require hair sampling from multiple anatomical locations; however, there remains a question as to whether this is necessary for isotopic studies of hair. The purpose of this study was to determine whether significant differences can be observed for the δ C, δ N and δ S values between paired hair samples taken from the rump and shoulder of grizzly bears (Ursus arctos).

Methods: Paired hair samples were collected from the rump and the shoulder of 81 grizzly bears in the Yukon, Canada. Hair samples were analyzed using a thermal combustion elemental analyzer coupled with a continuous flow isotope ratio mass spectrometer.

Results: Statistical comparisons of paired hair samples for both males and females showed no meaningful differences in δ C, δ N and δ S values in hair taken from the rump and shoulder, and any observed differences fell within the instrumental error.

Conclusions: Based on these results, hair may be safely sampled on either the rump or the shoulder without loss of isotopic information and thus this finding allows for refinement of sampling.